5 Trace activation and deactivation

3GPP52.008GSM subscriber and equipment traceRelease 17Telecommunication managementTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.1 General

This document is only concerned with the activation of a trace from an OSF (OMC), and the OSF shall keep a log of all trace activations and their deactivations. All entries in the log shall be date and time stamped.

In the case of an OSF (OMC) failure, it may be possible to activate and deactivate the trace at a particular network element by means of local MMI, but the procedures for doing this are not covered by the present document.

Facilities shall exist to allow unsolicited trace data to be received by an OSF. This permits the collection of trace data if the triggering entity (i.e. OSF or network element) is different to the collecting OSF.

5.2 Subscriber Tracing (Tracing of IMSI)

5.2.1 General

The tracing of both home and foreign roaming subscribers can be handled with this function.

If implemented, then the way the trace facility is used and organized, including restrictions due to national laws and regulations, will be a matter for the PLMN Operator.

All trace records created in the HLR, MSC "A", MSC "B" and BSS are forwarded to the OSF either as notifications and/or with bulk transfer, as defined in the trace parameters.

The following scenarios are identified from the HPLMN operation viewpoint:

a) HPLMN Operator traces its own (home) IMSI within the HPLMN;

b) HPLMN Operator traces the HLR activities of its own (home) IMSI while they are roaming in a VPLMN;

c) HPLMN Operator wishes to trace foreign roaming subscribers (IMSI) within its own HPLMN.

5.2.2 HPLMN Operator Traces Home Subscriber within the HPLMN

The Operator may activate a trace for a home subscriber (IMSI) from any OSF by invoking the management function Activate Home Subscriber Trace in the HLR where the IMSI is contained. This request includes the trace parameters in the following list:

a) IMSI to be traced;

b) Trace Reference;

c) OMC-Id of the destination OMC;

d) Trace Type;

e) HLR Trace Type.

For each IMSI, only one HPLMN subscriber trace can be active, subsequent requests being rejected.

If the IMSI is roaming within its HPLMN, then the trace request is forwarded to the VLR where the subscriber is registered via a MAP message (MAP-ACTIVATE-TRACE-MODE).

When the HPLMN subscriber trace is activated, a trace record will be created by MSC "A", MSC "B", HLR or BSS when certain invoking events occur i.e. MOC, MTC, SS-Action, SMS-MO, SMS-MT, Location Update, IMSI attach and detach. The trace action and record layout is defined by the trace type parameters.

A trace may be invoked in the BSS when an Invoking Event, specified in the Invoking Event sub-field in the Trace Type, occurs and the BSS Record Type is set to a value other than "No BSS Trace". A Trace is invoked by sending a BSSMAP MSC_INVOKE_TRACE message from the MSC to the BSS. When the BSS receives this message it starts tracing the necessary fields as specified in the BSS Record associated with the specified BSS Record Type.

If the subscriber is roaming in a foreign PLMN then the HPLMN subscriber trace request is stored in the HLR, but the trace is not active in the HPLMN VLRs.

The trace is deactivated by using the management function Deactivate Home Subscriber Trace in the HLR. This request includes the trace parameters in the following list:

a) IMSI;

b) Trace Reference.

If the IMSI is roaming within its HPLMN then the trace deactivation request is forwarded to the VLR where the subscriber is registered via a MAP message (MAP-DEACTIVATE-TRACE-MODE).

The trace shall be deactivated in the BSS by the MSC sending a BSSMAP MSC_INVOKE_TRACE message from the MSC to the BSS with the BSS Record Type set to "No BSS Trace". When the BSS receives this message it shall stop tracing activity related to that IMSI.

The following TMN Management Functions are required for trace activation (in HLR):

– Activate Home Subscriber Trace;

– Deactivate Home Subscriber Trace.

5.2.3 HPLMN Operator traces the HLR activities of own IMSI roaming in a VPLMN

This scenario is identical to the previous scenario with the exception that the only records generated come from the HLR.

5.2.4 PLMN Operator wishes to trace foreign subscribers (IMSI) in own PLMN

In order to trace the IMSIs of roaming subscribers in own PLMN, a list of those IMSIs plus the associated subscriber trace parameters must be stored in the VLR. No HLR trace records are produced for foreign subscriber traces.

The operator may activate a trace for any foreign roaming IMSI from an OSF by invoking the management function Activate Foreign Subscriber Trace in one or more VLRs within their own PLMN. If the location of the subscriber is not known it is necessary to activate the trace in all VLRs where the subscriber may be located.

The following trace parameters are sent with this request:

a) IMSI to be traced;

b) Trace Reference;

c) OMC-Id of the destination OMC;

d) Trace Type.

The trace request is stored in the VLR. If the subscriber subsequently roams into the VLR area the VPLMN subscriber trace will be activated.

For each IMSI only one foreign subscriber trace can be active in a particular VLR, subsequent requests being rejected.

The VPLMN subscriber trace is deactivated by invoking Deactivate Foreign Subscriber Trace in the VLR. This request includes the trace parameters in the following list:

a) IMSI;

b) Trace Reference.

The following TMN Management Functions are required for trace activation (in VLR):

– Activate Foreign Subscriber Trace;

– Deactivate Foreign Subscriber Trace.

5.3 Equipment Tracing (Tracing of IMEI)

5.3.1 General

If the tracing of IMEIs is implemented then the way the trace facility is used and organized, including restrictions due to national laws and regulations, will be a matter for the PLMN Operator.

An IMEI may be traced in order to find out the current IMSI, or the location or behaviour of faulty or stolen equipment reported via the EIR.

This TS describes one method of handling IMEI tracing i.e. tracing of IMEI via the VLR.

5.3.2 Tracing of IMEI via VLR

The operator may activate an equipment trace for any subscriber’s equipment (IMEI) from an OSF by invoking the management function Activate Equipment Trace in one or more VLR in the HPLMN. The trace must be activated in all VLRs controlling areas where it is required to trace the target IMEI. The trace parameters are transmitted with the activation request.

The following trace parameters are sent with this request:

a) IMEI to be traced;

b) Trace reference;

c) OMC-Id of the destination OMC;

d) Trace Type.

For GSM Phase 2 Mobile Stations the IMEI will be available to the Network as it can be included in the BSS-MAP message CIPHER-MODE-COMPLETE. If IMEI trace is required, it is the responsibility of the network operator to specify that CIPHER-MODE-COMPLETE contains IMEIs, or optionally the IMEI is called for in connection with MOC, location update etc. Alternatively the network can ask the MS for the IMEI by sending a TS 24.008 [19] IDENTITY REQUEST message to the MS, indicating that the IMEI is required.

When a subscriber arrives at a VLR using equipment with an IMEI for which trace has been activated (but is in pending state) at that VLR then the IMEI trace will become.

For each IMEI only one equipment trace can be active in a particular VLR at any one time, subsequent requests being rejected, although both the IMSI trace (home subscriber tracing and foreign subscriber tracing) and the IMEI trace can be active at the same time.

This equipment trace is deactivated by invoking the management function Deactivate Equipment Trace in the VLR. This request includes the trace parameters in the following list:

a) IMEI;

b) Trace Reference.

The following TMN Management Functions are required for trace activation (in VLR):

– Activate Equipment Trace;

– Deactivate Equipment Trace.

5.4 TMN Management Functions for Activation and Deactivation

5.4.1 List of Functions

5.4.1.1 HLR

The following functions are used for activation and deactivation in the HLR:

– Activate Home Subscriber Trace;

– Deactivate Home Subscriber Trace.

5.4.1.2 MSC/VLR

The following functions are used for activation and deactivation in the MSC/VLR:

– Activate Foreign Subscriber Trace;

– Deactivate Foreign Subscriber Trace;

– Activate Equipment Trace;

– Deactivate Equipment Trace.

5.4.2 Activate Home Subscriber Trace

This function is equivalent to the OM_Subscriber_Tracing_Activation_req in TS 29.002 [6].

The subscriber tracing procedures are used for the management of the trace status and the type of trace.

The subscriber tracing activation procedure operates as follows:

a) The OSF creates a tracedHomeSubscriberInHlr object instance in the HLR of the subscriber to be traced.

b) If the subscriber is roaming outside of the HPLMN or not currently registered, then the trace is in active pending state. The home subscriber trace for the subscriber is activated in the HLR on a subsequent location update. This activation is shown as an attribute value change in the attribute traceActivatedInVlr.

c) If the subscriber is already registered then the home subscriber trace becomes immediately active in the HLR (after positive confirmation from the VLR).

When the trace is first activated then the status of the trace indicator attribute traceActivatedInVlr in the tracedHomeSubscriberInHlr object instance is set to False.

If the subscriber is registered and is roaming in the home PLMN area then the HLR will initiate the request primitive MAP-ACTIVATE-TRACE-MODE and the trace indicator status will be set to True only in the case of a positive confirmation of the MAP-ACTIVATE-TRACE-MODE. In case of an error, the trace indicator status remains False.

If the MAP-ACTIVATE-TRACE-MODE confirm primitive is received indicating an error situation then this is recorded in an error attribute in the tracedHomeSubscriberInHlr object instance.

If the subscriber roams to an area outside that where tracing is possible then the status in the tracedHomeSubscriberInHlr object instance is updated to False.

The trace records are sent from the recording NEF to the OSF by the deployed event reporting mechanism (see chapter Trace Record Transfer). The Trace Type attribute indicates the type of trace records to be produced and the way in which they will be reported i.e. each event record being either directly sent to the OSF in real-time, or being collected in a file for later transfer.

All attribute value changes will be reported with a notification to the OSF.

The required system management functions are:

– Create tracedHomeSubscriberInHlr;

– Get Attribute.

The required notifications are:

– objectCreation;

– attributeValueChange.

5.4.3 Deactivate Home Subscriber Trace

This function is equivalent to the OM_Subscriber_Tracing_Deactivation_req in TS 29.002 [6].

The subscriber trace is deactivated by the OSF deleting the tracedHomeSubscriberInHlr object instance in the HLR.

If the trace status is True then the HLR will send the MAP-DEACTIVATE-TRACE-MODE message to VLR.

If the MAP-DEACTIVATE-TRACE-MODE confirm primitive is received indicating an error situation then this is indicated to the OSF via an error attribute in the tracedHomeSubscriberInHlr object instance and the object is not deleted.

The home subscriber trace deactivation can be indicated with a notification to the initiating OSF.

The required system management functions are:

– Delete tracedHomeSubscriberInHlr;

– Get Attribute.

The required notifications are:

– objectDeletion;

– attributeValueChange.

5.4.4 Activate Foreign Subscriber Trace

This function is analogous to the OM_Subscriber_Tracing_Activation_req in TS 29.002 [6], but the trace activation is performed directly in the VLR.

The foreign subscriber trace is activated by the OSF executing the system management function Create tracedForeignSubscriberInVlr in the VLR.

THE OSF creates a tracedForeignSubscriberInVlr object instance in the VLR(s) in which the network operator wishes to trace the subscriber.

The tracing continues as follows:

a) If the subscriber is not currently registered, then the foreign subscriber trace for the subscriber is active pending. It is activated (i.e. status attribute value is set to True) in the VLR on a subsequent location update. The activation is notified to the OSF as an attribute value change in the attribute foreignSubscriberRegisteredInVlr.

b) If the subscriber is already registered then the foreign subscriber trace becomes immediately active in the VLR.

When the trace is first activated then the status of the attribute foreignSubscriberRegisteredInVlr is set to False. When the traced subscriber registers in the VLR the attribute status of foreignSubscriberRegisteredInVlr is set to True.

All attribute value changes will be reported with a notification to the OSF.

The trace records are sent from the corresponding MSC to the OSF by the deployed event reporting mechanism (see chapter Trace Record Transfer). The Trace Type attribute indicates the type of trace records to be produced and the method by which they will be reported.

The required system management functions are:

– Create tracedForeignSubscriberInVlr;

– Get Attribute.

The required notifications are:

– objectCreation;

– attributeValueChange.

5.4.5 Deactivate Foreign Subscriber Trace

This function is analogous to the OM_Subscriber_Tracing_Deactivation_req in 29.002 [6], but the trace deactivation is performed.

The OSF deactivates subscriber trace by deleting the tracedForeignSubscriberInVlr object instance in the VLR(s) in which the object instance had previously been created.

The foreign subscriber trace is deactivated by the OSF executing the system management function Delete tracedForeignSubscriberInVlr in the VLR.

The required system management functions are:

– Delete tracedForeignSubscriberInVlr.

The required notifications are:

– objectDeletion;

– attributeValueChange.

5.4.6 Activate Equipment Trace

This function is analogous to the OM_Subscriber_Tracing_Activation_req in TS 29.002 [6], but the trace activation is performed directly in the VLR.

The equipment trace is activated by the OSF executing the system management function Create tracedEquipmentInVlr.

The OSF creates a traceEquipmentInVlr object instance in the VLR(s) for the areas to be monitored.

The tracing continues as follows:

a) If the equipment is not currently registered, then the equipment trace for the equipment is active pending. It is activated (i.e. status attribute value is set to True) in the VLR on a subsequent location update or IMSI attach. The activation is notified to the OSF as an attribute value change in the attribute equipmentRegisteredInVlr.

b) If the equipment is already registered then the equipment trace becomes immediately active in the VLR.

When the trace is first activated then the status of the attribute equipmentRegisteredInVlr is set to False. When the equipment registers in the VLR the attribute status of equipmentRegisteredInVlr is set to True.

All attribute value changes will be reported with a notification to the OSF.

The required system management functions are:

– Create tracedForeignSubscriberInVlr;

– Get Attribute.

The required notifications are:

– objectCreation;

– attributeValueChange.

5.4.7 Deactivate Equipment Trace

This function is analogous to the OM_Subscriber_Tracing_Deactivation_req in TS 29.002 [6], but the trace deactivation is performed in the VLR.

The equipment trace is deactivated by the OSF executing the system management function Delete tracedEquipmentInVlr.

The OSF deactivates equipment trace by deleting the tracedEquipmentInVlr object instance in the VLR(s) in which the object instance had previously been created.

The required system management functions are:

– Delete tracedEquipmentInVlr.

The required notifications are:

– objectDeletion;

– attributeValueChange.

This function is analogous to the OM_Subscriber_Tracing_Deactivation_req in TS 29.002 [6], but the trace deactivation is performed in the VLR.

5.5 HLR Functional Entities

Figure 2 shows that part of the Subscriber Administration Containment Tree for the HLR relevant to Trace activation and deactivation.

Figure 2: Subscriber Trace Containment Tree for the HLR

5.5.1 Managed Object Classes in HLR

5.5.1.1 tracedHomeSubscriberInHlr

This object class controls the home subscriber trace facility. Each instance of this object represents an IMSI of a home subscriber to be traced i.e. if an instance for an IMSI exists then that means that the trace has been activated for that IMSI.

Name	M/O	Value‑Set
IMSI	RDN	Single
traceActivatedInVlr	M	Single
traceReference	M	Single
traceType	M	Single
hlrTraceType	M	Single
operationSystemId	O	Single
mapErrorOnTrace	M	Single

5.5.1.2 Attributes

5.5.1.2.1 tracedHomeSubscriberInHlr

IMSI

This attribute is the RDN of the object tracedHomeSubscriberInHlr and defines an IMSI to be traced. It will be an IMSI of a home subscriber for whom tracing is required.

The syntax is defined in MAP‑CommonDataTypes IMSI.

traceActivatedInVlr

This attribute is single valued and gives an indication of the status of the Trace. Possible values of this attribute are True and False.

On creation this attribute is set to False.

If the subscriber is registered and roaming within the HPLMN (see TS 29.002 [6]) then the attribute is set to TRUE (in case of positive confirmation from VLR).

If the subscriber roams to an area which is outside that where tracing is possible the attribute is set to FALSE.

Each status change triggers an attributeValueChange notification.

traceReference

This attribute is a unique reference for a particular trace associated with a particular IMSI and is allocated by the OSF.

traceType

This attribute describes the invoking events for which the operator wishes to collect a trace record for a particular IMSI in an MSC or BSS. It also describes the type of record to be collected and indicates whether or not this is a priority trace.

hlrTraceType

This attribute describes the type of trace record (if any) the operator wishes to be collected in the HLR for a particular IMSI. It is assumed for all invoking events.

operationSystemId

This attribute contains the address of the OSF to which the operator wishes the trace records associated with this particular IMSI to be sent.

If EFDs are used then trace records are sent to OSFs defined in EFD.

mapErrorOnTrace

This attribute is single valued and read only.

It is set by MAP and contains the MAP‑Errors that may be returned in the confirm primitives of the ActivateTraceMode and DeactivateTraceMode Operations.

If there are MAP‑Errors in case of activation of trace, the traceActivatedInVlr parameter is set to False.

If there are Map‑Errors in case of deactivation of trace (deleting tracedHomeSubscriberInHlr), the deleting is not completed successfully.

Possible error values are defined in MAP‑OperationAndMaintenance Operations and in MAP‑Errors.

5.5.1.3 Notifications

The notifications (for each object) are:

– objectCreation;

– objectDeletion;

– AttributeValueChange.

5.6 VLR Functional Entities

Figure 3 shows that part of the Subscriber Administration Containment Tree for the VLR relevant to Trace.

Figure 3: Subscriber Trace Containment Tree for the VLR

5.6.1 Managed Object Classes in VLR

5.6.1.1 tracedForeignSubscriberInVlr

This object class controls the foreign subscriber trace facility. Each instance of this object represents an IMSI of a foreign subscriber to be traced i.e. if an instance for an IMSI exists then that means that the trace has been activated for that IMSI.

Name	M/O	Value‑Set
IMSI	RDN	Single
foreignSubscriberRegisteredInVlr	M	Single
traceReference	M	Single
traceType	M	Single
operationSystemId	O	Single

5.6.1.2 tracedEquipmentInVlr

This object class controls the equipment trace facility. Each instance of this object represents an IMEI to be traced i.e. if an instance for an IMEI exists then that means that the trace has been activated for that IMEI.

Name	M/O	Value‑Set
IMEI	RDN	Single
equipmentRegisteredInVlr	M	Single
traceReference	M	Single
traceType	M	Single
operationSystemId	O	Single

5.6.1.3 Attributes

5.6.1.3.1 tracedForeignSubscriberInVlr

IMSI

This attribute is the RDN of the object tracedForeignSubscriberInVlr and defines an IMSI to be traced. It will be an IMSI of a foreign subscriber for whom tracing is required.

The syntax is defined in MAP‑CommonDataTypes IMSI.

foreignSubscriberRegisteredInVlr

This attribute is single valued and gives an indication of the status of the Trace. Possible values of this attribute are True and False.

On creation this attribute is set to False.

If the foreign subscriber is currently registered in the VLR then the attribute is set to TRUE.

If the foreign subscriber is not registered in the VLR then the attribute is set to FALSE.

Each status change triggers an attributeValueChange notification.

traceReference

This attribute is a unique reference for a particular trace associated with a particular IMSI and is allocated by the OSF.

traceType

This attribute describes the invoking events that the operator wishes to collect a trace record for a particular IMSI in an MSC or BSS. It also describes the type of record to be collected and indicates whether or not this is a priority trace.

operationSystemId

This attribute contains the address of the OSF to which the operator wishes the trace records associated with this particular IMSI to be sent.

If EFDs are used, then trace records are sent to OSFs defined in EFD.

5.6.1.3.2 tracedEquipmentInVlr

IMEI

This attribute is the RDN of the object tracedEquipmentInVlr and defines an IMEI to be traced. It will be an IMEI for the equipment for which tracing is required.

The syntax is defined in MAP‑CommonDataTypes IMEI.

equipmentRegisteredInVlr

This attribute is single valued and gives an indication of the status of the Trace. Possible values of this attribute are True and False.

On creation this attribute is set to False.

If the equipment is registered in the VLR then the attribute is set to TRUE.

If the equipment is not registered in the VLR then the attribute is set to FALSE.

Each status change triggers an attributeValueChange notification.

traceReference

This attribute is a unique reference for a particular trace associated with a particular IMSI and is allocated by the OSF.

traceType

operationSystemId

This attribute contains the address of the OSF to which the operator wishes the trace records associated with this particular IMSI to be sent.

If EFDs are used, then trace records are sent to OSFs defined in EFD.

5.6.1.4 Notifications

The notifications are:

– objectCreation;

– objectDeletion;

– attributeValueChange.